How do I know when i ovulated?

Kennedy • Married to my soulmate since 7.4.2020!💍💞 We have a 4 year old son, who took a year and a half to conceive! We are expecting baby girl March 11th 2021 after 2 1/2 years of ttc with fertility treatments 💖
So my fertile window was from Sep. 27- Oct. 3. I didn't take any OPKs (which i should have)and I'm not sure when I ovulated . Glow gave me a 33% chance on Oct. 1st ( I'm not sure if because i ovulate that day or because i ovulate the next day but it gives me a better percentage to have sex the day before ovulation) by my count with splitting a normal 28 day cycle counting 14 days since the first day of my period i got Oct. 2nd. And another app told me the 3rd. I'm so lost!?